In the case of the kenaf plant it is composed of stalk having a fibrous bark and core, of which the former possesses long fibres capable of producing a high quality paper pulp, while the latter is of lesser quality short fibre composition. In some areas of the world the process of recovering the bark fibre comprises cutting and bundling of the stalks, which are dried in the field and then retted with the bark fibre being scutched from the central woody stem. This is a time-consuming task and the bark fibre that is obtained is not in best form for paper pulping.
Proposals have been made for machine processing of the harvested stalks and this has entailed firstly crushing, grinding or chopping of the stalks, and subsequently separation of the bulk material into separate phases. A similar form of crushing mill to that utilised in the sugar cane industry has, in one instance, been utilised, although modified, for the first stage of processing, while in another instance a forage harvester has been used to gather the crop for baling in a finely chopped condition. It has not been possible to achieve high quality grading with conventional separation apparatus.